What altitude will it be driven at mostly? Can you and will you degree the new cam? I helped a freind of mine years ago who had a 1976 or 1977 short box 360 4x4 pickup with 34 inch tires on it, it came with 3.07 gears front and rear and he ended up changing them to 3.91 at first and ended up with 4.10 finally after bending the rear 8 3/4 rear he had he put in it . It had headers and a Thermoquad we worked on a little, he loved whupping the BB Chevy and Fords 4x4 in the river bottoms in pull offs and sand dragging them and on the hills with his truck